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Abstract:

A radio device, which is the source, transmits a route request packet
(RREQ) to a radio device. In response to the route request packet (RREQ),
the radio device transmits to the radio device a route setup packet
(RSET) including a route Radio Device Radio Device Radio Device Radio
Device by looking-up topology information (TPIF). In response to the
route setup packet (RSET), the radio device produces a route notification
packet (RNTF) and transmits the produced route notification packet (RNTF)
to radio devices, and. In response to the route notification packet
(RNTF), the radio device, which is the destination, produces a route
reply packet (RREP) and transmits the produced route reply packet (RREP)
to the radio device, which is the source.

Claims:

1. A wireless network system carrying out multi-hop wireless communication
between a source and a destination, comprising:a first radio device
maintaining topology information (TPIF) indicating the arrangement of all
radio devices constituting the wireless network system, when a route for
wireless communication is established between the source and the
destination, transmitting route information indicating the route based on
the topology information (TPIF); anda plurality of second radio devices
establishing the route based on the route information transmitted by the
first radio device.

2. The wireless network system according to claim 1, whereineach of the
first radio device and the plurality of second radio devices is suitable
to wireless communication based on link state information related to
their respective adjacent radio devices.

3. The wireless network system according to claim 2, wherein,upon carrying
out wireless communication with the destination, the source radio device
that is one of the plurality of second radio devices receives, from the
first radio device, route information indicating the route from the radio
device itself to the destination radio device and establishes the route
to the destination radio device based on the received route information.

4. The wireless network system according to claim 3, wherein the source
radio device transmits to the first radio device a route request packet
(RREQ), receives from the first radio device a route setup packet (RSET)
including the route information, transmits a route notification packet
(RNTF) notifying each radio device on the route that wireless
communication is carried out along the route indicated by the route
information included in the received route setup packet (RSET), and
receives from the destination radio device a route reply packet (RREP)
accepting the establishment of the route indicated by the route
information;in response to the route request packet (RREQ), the first
radio device extracts route information indicating the optimal route from
the source radio device to the destination radio device by looking-up the
topology information (TPIF), produces the route setup packet(RSET)
including the extracted route information, and transmits the produced
route setup packet (RSET) to the source radio device; andupon receiving
the route notification packet (RNTF), the destination radio device
produces the route reply packet (RREP) and transmits the produced route
reply packet (RREP) to the source radio device.

5. The wireless network system according to claim 3, wherein the source
radio device transmits to the first radio device a route request packet
(RREQ), receives from the first radio device a route setup packet (RSET)
including the route information, transmits a route notification packet
(RNTF) notifying each radio device on the route that wireless
communication is carried out along the route indicated by the route
information included in the received route setup packet (RSET), and
receives from the destination radio device a route reply packet (RREP)
accepting the establishment of the route indicated by the route
information;in response to the route request packet (RREQ), the first
radio device extracts route information indicating the optimal route from
the source radio device to the destination radio device by looking-up the
topology information (TPIF), produces the route setup packet (RSET)
including the extracted route information and transmits the produced
route setup packet (RSET) to the source radio device;upon receiving the
route notification packet (RNTF), the radio device adjacent, on the
route, to the destination radio device transmits a route request packet
(RREQ) to the destination radio device; andin response to the route
request packet (RREQ), the destination radio device produces the route
reply packet (RREP) and transmits the produced route reply packet (RREP)
to the source radio device.

6. The wireless network system according to claim 2, wherein, based on the
topology information (TPIF), the first radio device produces a routing
table including route information indicating the route for which the
destination is each radio device in the wireless network system and
transmit the produced routing table to the plurality of second radio
devices; andeach of the plurality of second radio devices receives the
routing table from the first radio device and establishes the route to
the destination radio device based on the received routing table.

7. The wireless network system according to claim 1, whereinthe first
radio device is suitable to wireless communication based on link state
information related to a radio device adjacent to the first radio device
itself; andthe plurality of second radio devices comprisesi (i is a
positive integer) third radio devices each suitable to wireless
communication based on the link state information, andj (j is a positive
integer) fourth radio devices each unsuitable to wireless communication
based on the link state information.

8. The wireless network system according to claim 7, wherein a radio
device adjacent to one of the j fourth radio devices is one of the i
third radio devices.

9. The wireless network system according to claim 8, wherein,when the
source radio device that is one of the j fourth radio devices carries out
wireless communication with the destination, a first adjacent radio
device that is adjacent to the source radio device and is one of the i
third radio devices receives, from the first radio device, route
information indicating the route from the source radio device to the
destination radio device and established the route to the destination
radio device based on the received route information.

10. The wireless network system according to claim 9, whereinthe source
radio device transmits a route request packet (RREQ) to the first radio
device;the first adjacent radio device receives from the first radio
device a route setup packet (RSET) including the route information,
transmits a route notification packet (RNTF) notifying each radio device
on the route that wireless communication is carried out along the route
indicated by the route information included in the received route setup
packet (RSET), receives from the destination radio device a route reply
packet (RREP) accepting the establishment of the route indicated by the
route information, and relays the received route reply packet (RREP) to
the source radio device;in response to the route request packet (RREQ),
the first radio device extracts route information indicating the optimal
route from the source radio device to the destination radio device by
looking-up the topology information (TPIF), produces the route setup
packet (RSET) including the extracted route information and transmits the
produced route setup packet (RSET) to the first adjacent radio
device;upon receiving the route notification packet (RNTF), the
destination radio device produces the route reply packet (RREP) and
transmits the produced route reply packet (RREP) to the source radio
device.

11. The wireless network system according to claim 10, wherein,when the
destination radio device is one of the j fourth radio devices, upon
receiving the route notification packet (RNTF), a second adjacent radio
device that is adjacent, on the route, to the destination radio device
and is one of the i third radio devices transmits a route request packet
(RREQ) to the destination radio device.

12. The wireless network system according to claim 7, wherein,based on the
topology information (TPIF), the first radio device produces a routing
table including route information indicating the route for which the
destination is each radio device in the wireless network system and
transmits the produced routing table to the i third radio devices;
andeach of the i third radio devices receives from the first radio device
the routing table and establishes the route to the destination radio
device based on the received routing table.

13. The wireless network system according to claim 8, wherein,based on the
topology information (TPIF), the first radio device produces a routing
table including route information indicating the route for which the
destination is each radio device in the wireless network system and
transmits the produced routing table to the i third radio devices;
andeach of the i third radio devices receives from the first radio device
the routing table and establishes the route to the destination radio
device based on the received routing table.

Description:

[0002]Ad hoc networks are constructed autonomously and instantly in
response to communications between a plurality of radio devices. In ad
hoc networks, when two interacting radio devices are not located in the
same communication area, a radio device that is located between the two
radio devices functions as a router and relays data packets. In this way,
large multi-hop networks are formed.

[0003]Dynamic routing protocols that support multi-hop communications are
classified into two categories: table-driven protocols and on-demand
protocols. Table-driven protocols periodically exchange route control
information and preestablish the routing table. Known table-driven
protocols include FSR (Fish-eye State Routing), OLSR (Optimized Link
State Routing) and TBRPF (Topology Dissemination Based on Reverse-Path
Forwarding).

[0005]In conventional ad hoc networks, when data is transmitted from
source to destination, the communication route is determined so that the
number of hops from source to destination is as small as possible
(Guangyu Pei, et al., "Fisheye state routing: a routing scheme for ad hoc
wireless networks,"0 ICC2000. Commun., Volume 1, L.A., June 2000, pp.
70-74.)

[0006]However, as the wireless environment is unstable, the route with
small hop numbers does not necessarily guarantee the quality. Therefore,
it is better to select only stable routes in some way. Known major
methods thereof are methods of introducing signal strength thresholds and
methods of measuring packet loss rates.

[0010]Unfortunately, in wireless network systems where radio devices carry
out, according to a table-driven routing protocol, wireless
communications based on link state information of neighboring radio
devices, it is problematic that loads to the wireless network systems is
heavy. This is because, in such wireless network systems, a plurality of
radio devices each periodically communicates link state information with
other radio devices, produces a topology table presenting the arrangement
of the radio devices in the wireless network systems based on the link
state information received from other radio devices, and monitors the
produced topology table. This results in heavy load to all the plurality
of radio devices in the network systems.

[0011]The present invention is aimed at solving the afore-mentioned
problem. One of its objects is to provide a wireless network system that
enables load reduction.

[0012]According to the present invention, a wireless network system
carrying out multi-hop wireless communication between source and
destination comprises a first radio device and a plurality of second
radio devices. The first radio device maintains topology information
indicating the arrangement of all the radio devices constituting the
wireless network system and, when the route for wireless communication is
established between source and destination, transmits route information
indicating the route based on the topology information. The plurality of
second radio devices establish the route based on the route information
transmitted by the first radio device.

[0013]Preferably, each of the first radio device and the plurality of
second radio devices is suitable to wireless communication based on link
state information related to their respective adjacent radio devices.

[0014]Preferably, upon carrying out wireless communication with the
destination, the source radio device that is one the plurality of second
radio devices receives, from the first radio device, route information
indicating the route from the source radio device itself to the
destination radio device and establishes the route to the destination
radio device based on the received route information.

[0015]Preferably, the source radio device transmits a route request packet
to the first radio device, receives from the first radio device a route
setup packet including route information, transmits a route notification
packet notifying each radio device on the route that the wireless
communication is carried out along the route indicated by the route
information included in the received route setup packet, and receives
from the destination radio device a route reply packet accepting the
establishment of the route indicated by the route information. In
response to the route request packet, the first radio device extracts the
route information indicating the optimal route from the source radio
device to the destination radio device by looking-up the topology
information, produces the route setup packet including the extracted
route information and transmits the produced route setup packet to the
source radio device. Upon receiving the route notification packet, the
destination radio device produces the route reply packet and transmits
the produced route reply packet to the source radio device.

[0016]Preferably, the source radio device transmits a route request packet
to the first radio device, receives from the first radio device a route
setup packet including the route information, transmits a route
notification packet notifying each radio device on the route that
wireless communication is carried out along the route indicated by the
route information included in the received route setup packet, and
receives from the destination radio device a route reply packet accepting
the establishment of the route indicated by the route information. In
response to the route request packet, the he first radio device extracts
route information indicating the optimal route from the source radio
device to the destination radio device by looking-up the topology
information, produces the route setup packet including the extracted
route information and transmits the produced route setup packet to the
source radio device. Upon receiving the route notification packet, an
adjacent radio device adjacent, on the route, to the destination radio
device transmits the route request packet to the destination radio
device. In response to the route request packet, the destination radio
device produces the route reply packet and transmits the produced route
reply packet to the source radio device.

[0017]Preferably, based on the topology information, the first radio
device produced a routing table including route information indicating
the routes for which the destination is each radio device in the wireless
network system and transmits the produced routing table to the plurality
of second radio devices. Each of the plurality of second radio devices
receives the routing table from the first radio device and, based on the
received routing table, establishes the route to the destination radio
device.

[0018]Preferably, the first radio device is suitable to wireless
communication based on link state information related to a radio device
adjacent to the first radio device itself. The plurality of second radio
devices comprise i (i is a positive integer) third radio devices each
suitable to wireless communication based on the link state information
and j (j is a positive integer) fourth radio devices each unsuitable to
wireless communication base on the link state information.

[0019]Preferably, a radio device adjacent to one of the j fourth radio
device is one of the i third radio devices.

[0020]Preferably, when the source radio device that is one of the j fourth
radio devices carries out wireless communication with the destination, a
first adjacent radio device that is adjacent to the source radio device
and is one of the i third radio devices receives, from the first radio
device, route information indicating the route from the source radio
device to the destination radio device and establishes the route to the
destination radio device based on the received route information.

[0021]Preferably, the source radio device transmits a route request packet
to the first radio device. The first adjacent radio device receives from
the first radio device a route setup packet including route information,
transmits a route notification packet notifying each radio device on the
route that wireless communication is carried out along the route
indicated by the route information included in the received route setup
packet, receives from the destination radio device a route reply packet
accepting the establishment of the route indicated by the route
information, and relays the received route reply packet to the source
radio device. In response to the route request packet, the first radio
device extracts route information indicating the optimal route from the
source radio device to the destination radio device by looking-up the
topology information, produces the route setup packet including the
extracted route information and transmits the produced route setup packet
to the first adjacent radio device. Upon receiving the route notification
packet, the destination radio device produces the route reply packet and
transmits the produced route reply packet to the source radio device.

[0022]Preferably, when the destination radio device is one of the j fourth
radio device, upon receiving the route notification packet, a second
adjacent radio device that is adjacent, on the route, to the destination
radio device and is one of the i third radio devices transmits a route
request packet to the destination radio device.

[0023]Preferably, based on the topology information, the first radio
device produces a routing table including route information indicating
the route for which the destination is each radio device in the wireless
network system and transmits the produced routing table to the i third
radio devices. Each of the i third radio devices receives the routing
table from the first radio device and, base on the received routing
table, establishes the route to the destination radio device.

[0024]In the wireless network system according to the present invention,
one radio device (the first radio device) produces and maintains topology
information indicating the arrangement of all radio devices constituting
the wireless network system. None of the plurality of second radio
devices produce nor maintain the topology information.

[0025]Therefore, according to the present invention, the load to the
plurality of second radio devices is reduced. As a result, compared to
the case where all of the first radio device and the plurality of second
radio devices produce and maintain the topology information, the load to
the wireless network system is reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026]FIG. 1 is a schematic diagram of a wireless network system according
to Embodiment 1 of the present invention.

[0027]FIG. 2 is a schematic block diagram illustrating the structure of
the lo radio device shown in FIG. 1.

[0028]FIG. 3 illustrates the structure of the routing table shown in FIG.
2.

[0036]FIG. 11A is a schematic diagram according to Embodiment 1
illustrating how the route for wireless communication is established
between source and destination.

[0037]FIG. 11B is a schematic diagram according to Embodiment 1
illustrating how the route for wireless communication is established
between source and destination.

[0038]FIG. 11C is a schematic diagram according to Embodiment 1
illustrating how the route for wireless communication is established
between source and destination.

[0039]FIG. 11D is a schematic diagram according to Embodiment 1
illustrating how the route for wireless communication is established
between source and destination.

[0040]FIG. 12 shows another example of the routing table.

[0041]FIG. 13A illustrates another example of the routing table.

[0042]FIG. 13B illustrates another example of the routing table.

[0043]FIG. 13C illustrates another example of the routing table.

[0044]FIG. 13D illustrates another example of the routing table.

[0045]FIG. 14 is a schematic diagram of a wireless network system
according to Embodiment 2.

[0046]FIG. 15 is a schematic block diagram illustrating the structure of
some radio devices of the radio devices shown in FIG. 14.

[0047]FIG. 16A illustrates how the Root radio device gathers link state
information in Embodiment 2.

[0048]FIG. 16B illustrates how the Root radio device gathers link state
information in Embodiment 2.

[0049]FIG. 16C illustrates how the Root radio device gathers link state
information in Embodiment 2.

[0050]FIG. 16D illustrates how the Root radio device gathers link state
information in Embodiment 2.

[0051]FIG. 17A is a schematic diagram according to Embodiment 2
illustrating how the route for wireless communication is established
between source and destination.

[0052]FIG. 17B is a schematic diagram according to Embodiment 2
illustrating how the route for wireless communication is established
between source and destination.

[0053]FIG. 17C is a schematic diagram according to Embodiment 2
illustrating how the route for wireless communication is established
between source and destination.

[0054]FIG. 17D is a schematic diagram according to Embodiment 2
illustrating how the route for wireless communication is established
between source and destination.

[0055]FIG. 18A is another schematic diagram according to Embodiment 2
illustrating how the route for wireless communication is established
between source and destination.

[0056]FIG. 18B is another schematic diagram according to Embodiment 2
illustrating how the route for wireless communication is established
between source and destination.

[0057]FIG. 18C is another schematic diagram according to Embodiment 2
illustrating how the route for wireless communication is established
between source and destination.

[0058]FIG. 18D is another schematic diagram according to Embodiment 2
illustrating how the route for wireless communication is established
between source and destination.

[0059]FIG. 19 is another schematic block diagram illustrating the
structure of the radio devices shown in FIG. 1.

[0060]FIG. 20 is another schematic block diagram illustrating the
structure of some radio devices of the radio devices shown in FIG. 14.

BEST MODES FOR CARRYING OUT THE INVENTION

[0061]The present invention will now be described in embodiments with
reference to the drawings more specifically. In the figures, identical or
like components are identically denoted by the same reference numbers and
explanations thereof are not repeated.

EMBODIMENT 1

[0062]FIG. 1 is a schematic diagram of a wireless network system according
to Embodiment 1 of the present invention. With reference to FIG. 1, the
wireless network system 10 according to Embodiment 1 of the present
invention comprises radio devices 0 to 9. The radio devices 0 to 9 are
located in a wireless communication space and constitute a mesh network.
The radio device 0 comprises a gateway and is connected to a cable 100.
Note that a radio device x constitutes another wireless network system
and is a gateway connected to the cable 100.

[0063]For example, when data is transmitted from the radio device 3 to the
radio device 5, the radio devices 4 and 7 relay packets received from the
radio device 3 to the radio device 5. Likewise, in the wireless network
system 10, a plurality of radio devices relays packets from the source
and, in this way, the packets are sent from source to destination. More
specifically, in the wireless network system 10, multi-hop wireless
communications are carried out between source and destination.

[0064]Each of the radio devices 0 to 9 comprises a radio device suitable
to wireless communication based on link state information, which is
related to radio devices adjacent to the radio devices 0 to 9 themselves.
Each of the radio devices 0 to 9 has both functions of a table-driven
routing protocol and an on-demand routing protocol.

[0065]Note that, here, the OLSR protocol is used as the table-driven
routing protocol, and the AODV protocol is used as the on-demand routing
protocol.

[0066]FIG. 2 is a schematic block diagram illustrating the structure of
the radio device 0 shown in FIG. 1. The radio device 0 includes an
antenna 11, an input unit 12, an output unit 13, a user application 14,
and a communication control unit 15.

[0067]The antenna 11 receives data from other radio devices over a
wireless communication space, outputs the received data to the
communication control unit 15 and transmits data received from the
communication control unit 15 to other radio devices over the wireless
communication space.

[0068]The input unit 12 receives a message and a destination of data that
have been input by a user of the radio device 0 and outputs the received
message and destination to the user application 14. The output unit 13
displays the message in accordance with control by the user application
14.

[0069]The user application 14 produces data based on the message and
address received form the input unit 12 and outputs the produced data to
the communication control unit 15.

[0071]Belonging to the physical layer, the wireless interface module 16
modulates/demodulates transmitting signals or receiving signals in
accordance with a prescribed regulation and transmits/receives signals
through the antenna 11.

[0072]The MAC module 17 belongs to the MAC layer and executes various
functions described below by executing the MAC protocol.

[0073]More specifically, the MAC module 17 receives a Hello packet from
the routing daemon 23 and broadcasts the Hello packet through the
wireless interface module 16.

[0075]The LLC module 19, which belongs to the data link layer, executes
the LLC protocol and connects/disconnects links with adjacent radio
devices.

[0076]The IP module 19 belongs to the Internet layer and produces an IP
packet. The IP packet includes an IP header and an IP data unit to store
packets sent by the upper protocols. Upon receiving data from the TCP
module 21, the IP module 19 produces the IP packet by storing the
received data into the IP data unit.

[0077]Then, the IP module 19 searches among the routing table 20 in
accordance with the OLSR protocol and selects a route to transmit the
produced IP packet. The IP module 19 then transmits the IP packet to the
LLC module 18 in order to transmit the IP packet to the destination along
the selected route.

[0079]The TCP module 21 belongs to the transport layer and produces a TCP
packet, which includes a TCP header and a TCP data unit to store data
sent by the upper protocols. The TCP module 21 then transmits the
produced TCP packet to the IP module 19.

[0080]The UDP module 22, which belongs to the transport layer, broadcasts
an Update packet produced by the routing daemon 23. The UDP module 22
also receives Update packets broadcast by other radio devices and outputs
the received Update packets to the routing daemon 23.

[0081]The routing daemon 23, which belongs to the process/application
layer, monitors the execution status of other communication control
modules and processes requests from other communication control modules.

[0082]The routing daemon 23 also periodically transmits requests for
obtaining link state information to other radio devices and receives link
state information from other radio devices. Then, with the methods
described below, the routing daemon 23 produces a topology table that
indicates the arrangement of all the radio devices 0 to 9 in the wireless
network system 10 based on the link state information received from other
radio devices (the radio devices 1 to 9) and maintains the produced
topology table.

[0083]Further, upon receiving a route request packet RREQ from other radio
devices, the routing daemon 23 detects, based on the topology table,
route information presenting the optimal route for wireless communication
between other radio devices and their respective destinations. The
routing daemon 23 then produces a route setup packet RSET including the
detected route information.

[0084]It should be noted that each of the radio devices 1 to 9 shown in
FIG. 1 has the same structure as the radio device 0 shown in FIG. 2. None
of the radio devices 1 to 9, however, has the functions to produce a
topology table and to maintain the produced topology table. Accordingly,
with the present invention, only the radio device 0 produces and
maintains the topology table

[0085]FIG. 3 illustrates the structure of the routing table 20 shown in
FIG. 2. With reference to FIG. 3, the routing table 20 includes
Destination, Next Radio Device and Number of Hops, which are associated
with each other.

[0086]The Destination represents the IP address of the destination radio
device. The Next Radio Device is the IP address of the radio device to
which packets must be transmitted next toward the destination. The Number
of Hops represents the number of hops to the destination. For example,
with reference to FIG. 1, when wireless communication is carried out
between the radio device 3 and the radio device 5 along route Radio
Device 3-Radio Device 4-Radio Device 7-Radio Device 5, a value 3 is
stored into the Number of Hops in the routing table 20 of the radio
device 3.

[0088]Each of the ID, Length, Mode Flag, Number of Destinations, and
Number of Hops has a data length of 1 octet. The RREQ-ID has a data
length of 4 octets. The Source Address has a data length of 6 octets.
Each of the Source Sequence Number and Metric has a data length of 4
octets. Each of the Destination Address #1 to Destination Address #N has
a data length of 6 octets. Each of the Destination Sequence Number #1 to
Destination Sequence Number #N has a data length of 4 octets.

[0089]The ID comprises an identifier that identifies the route request
packet RREQ. The Length represents the length of the route request packet
RREQ and is a variable value. The Mode Flag is any of Bit 0, Bit 1, and
Bit 2 to 7. The Bit 0 represents the request mode. The Bit 1 represents
the broadcast mode. The Bit 2 to 7 is reserved.

[0090]The Number of Destinations is the number of combinations of the
destination addresses and the destination sequence numbers. The Number of
Hops is the number of hops from the source MAC address to the radio
devices relaying the route request packet. Therefore, the Number of Hops
is incremented by 1 for each relay of the route request packet RREQ.

[0091]The RREQ-ID is associated with the MAC address of the radio device
that has produced the route request packet RREQ and is an eigenvalue to
indentify the route request packet RREQ. Therefore, the RREQ-ID is never
changed.

[0092]The Source Address includes the MAC address of the source radio
device. The Source Sequence Number includes a series of sequence numbers
used to enter the route implying the source of the route request packet
RREQ.

[0093]The Metric includes the cumulative metric from the source radio
device to the radio devices relaying the route request packet RREQ.
Therefore, the Metric is incremented for each relay of the route request
packet RREQ.

[0094]Each of the Destination Address #1 to Destination Address #N
includes the MAC address of the destination of the requested route.

[0095]Each of the Destination Sequence Number #1 to Destination Sequence
Number #N includes the latest sequence number of sequence numbers
received in the past by the source of the route toward the destination
radio device. It should be noted that when each of the Destination
Sequence Number #1 to Destination Sequence Number #N stores 0, each of
the Destination Sequence Number #1 to Destination Sequence Number #N
indicates that the source does not know the sequence number of the
destination.

[0097]Each of the ID, Length, Mode Flag, and Number of Sources has a data
length of 1 octet. The Destination Address has a data length of 6 octets.
Each of the Destination Sequence Number, Lifetime and Metric has a data
length of 4 octets. Each of the Source Address #1 to Source Address #N
has a data length of 6 octets. Each of the Source Sequence Number #1 to
Source Sequence Number #N has a data length of 4 octets.

[0098]The ID includes an identifier that identifies the route reply packet
RREP. The Length represents the length of the route reply packet RREP and
is a variable value. The Mode Flag is any of Bit 0, Bit 1, and Bit 2 to
7. The Bit 0 represents the request mode. The Bit 1 represents the
transfer mode. The Bit 2 to 7 is reserved.

[0099]The Number of Sources is the number of combinations of the source
addresses and source sequence numbers. The Destination Address includes
the MAC address of the destination radio device of the requested route.
The Destination Sequence Number includes the latest sequence number of
sequence numbers received in the past by the source of the route toward
the destination radio device. It should be noted that when the
Destination Address stores 0, the Destination Address indicates that the
source does not know the sequence number of the destination.

[0100]The Lifetime is the time it takes for the radio device receiving the
route reply packet RREP to determine whether the route is valid or not
and is on the millisecond time scale. The Metric is the cumulative Metric
from the destination radio device to the radio device relaying the route
reply packet RREP. Therefore, the Metric is incremented for each relay of
the route reply packet RREP.

[0101]Each of the Source Address #1 to Source Address #N includes the MAC
address of the source of the route request packet RREQ at a time when the
route was provided. Each of the Source Sequence Number #1 to Source
Sequence Number #N includes a series of sequence numbers that is used to
enter the route implying the source of the route request packet RREQ.

[0103]Each of the ID, Length, Mode Flag, RSET-ID, and RREQ-ID has a data
length of 1 octet. The Root Address has a data length of 6 octets. The
Root Sequence Number has a data length of 4 octets. The Number of Radio
Devices has a data length of 1 octet. Each of the RNTF Address and Radio
Device Address #1 to Radio Device Address #N has a data length of 6
octets.

[0104]The ID includes an identifier that identifies the route setup packet
RSET. The Length represents the length of the route setup packet RSET and
is a variable value. The Mode Flag includes any one of Bit 0, Bit 1 and
Bit 2 to 7. The Bit 0 represents the unicast mode. The Bit 1 represents
the broadcast mode. The Bit 2 to 7 is reserved.

[0105]The RSET-ID is associated with the MAC address of the radio device
that has produced the route setup packet RSET and includes an eigenvalue
to identify the route setup packet RSET. Therefore, the RSET-ID is never
changed.

[0106]The RREQ-ID includes the RREQ-ID received by the Root radio device.
The Root Address includes the MAC address of the Root radio device that
searches for a better route.

[0107]The Root Sequence Number includes a series of sequence numbers used
to enter the route implying the Root radio device.

[0108]The Number of Radio Devices is the number of radio devices that
exist on the set route. The RNTF Address includes the MAC address of the
radio device that starts to send the route notification packet notifying
that a route setup is requested.

[0109]Each of the Radio Device Address #1 to Radio Device Address #N
includes the MAC address of the radio devices that exist on the route for
which the setup is requested.

[0111]Each of the ID, Length, Mode Flag, RNTF-ID, RREQ-ID, and Number of
Radio Devices has a data length of 1 octet. The Lifetime has a data
length of 4 octets. The RNTF Address has a data length of 6 octets. The
RNTF Sequence Number has a data length of 4 octets. Each of the Radio
Device Address #1 to Radio Device Address #N has a data length of 6
octets.

[0112]The ID includes an identifier that indentifies the route
notification packet RNTF. The Length represents the length of the route
notification packet RNTF and is a variable value. The Mode Flag includes
any one of Bit 0, Bit 1, and Bit 2 to 7. The Bit 0 represents the unicast
mode. The Bit 1 represents the broadcast mode. The Bit 2 to 7 is
reserved.

[0113]The RNTF-ID is associated with the MAC address of the source radio
device of the route notification packet RNTF and includes an eigenvalue
to identify the route notification packet RNTF. Therefore, the RNTF-ID is
never changed.

[0114]The RREQ-ID includes the RREQ-ID received by the Root radio device.
The Number of Radio Devices is the number of radio devices that exist on
the set route. The Lifetime is the time it takes for the radio devices
receiving the route notification packet RNTF to determine whether the
route is valid or not and is on the millisecond time scale. The RNTF
Address includes the MAC address of the radio device that has produced
the route notification packet RNTF to notify that a route setup is
requested.

[0115]The RNTF Sequence Number includes a series of sequence numbers used
to enter the route implying the source of the route request packet RREQ.
Each of the Radio Device Address #1 to Radio Device Address #N includes
the MAC address of the radio devices that exist on the route for which
the setup is requested.

[0117]Each of the Element ID, Length and Flag has a data length of 1
octet. The Mesh Portal Bridge ID has a data length of 6 octets. Each of
the Priority and Number of Mesh Portals has a data length of 1 octet. The
Mesh Portal Address has a data length of 6 octets. Each of the Root
Sequence Number and Root Metric has a data length of 4 octets. The
Topology Maintenance Method has a data length of 1 octet. The Connected
Mesh Portal ID has a data length of 6×N octets.

[0118]The Element ID includes an identifier that identifies the route
announcement packet RAE. The Length represents the length of respective
information. The Flag includes any one of Bit 0, Bit 1 and Bit 2 to 7.
The Bit 0 represents the type of the announcement. The Bit 1 represents
the HWMP (Hybrid Wireless Mesh Protocol) registration. The Bit 2 to 7 is
reserved.

[0119]The Mesh Portal Bridge ID is unique bridge ID of Mesh Portals. As
for the Priority, a Mesh Portal that has the lowest priority is to be the
default Mesh Portal: a value of 0 means that the Mesh Portal is
configured as a Root radio device.

[0120]The Number of Mesh Portals is the number of the connected Mesh
Portals which have wired and wireless connectivity. The Mesh Portal
Address includes the MAC address of Mesh Portals. The Root Sequence
Number is the latest sequence number of sequence numbers received in the
past by the source of routes towards the Root radio device.

[0121]The Metric is the cumulative metric from the Root radio device to
the radio device transmitting the route announcement packet RAE.
Therefore, the Metric is incremented for each relay of the route
announcement packet RAE.

[0122]The Topology Maintenance Method includes any one of 0 to 3. The
values 0 to 3 represent Methods 1 to 4, respectively. The Connected Mesh
Portal ID is the list of MAC addresses of Mesh Portals that have both
wired and wireless connectivity: a value of 0 means that the route
announcement packet RAE has been transmitted by the Root radio device.

[0123]FIG. 9 shows an example of link state information LSIF. With
reference to FIG. 9, the link state information LSIF includes a radio
device adjacent to each of the radio devices 0 to 9 in the wireless
network system 10.

[0124]For example, the radio device 0, the radio device 2, the radio
device 4, and the radio device 3 are each adjacent to the radio device 1.
Likewise, the radio device 1, the radio device 2, the radio device 3, the
radio device 6, and the radio device 7 are each adjacent to the radio
device 4. Therefore, the link state information LSIF includes 1-0, 1-2,
1-4, 1-3, 4-1, 4-2, 4-3, 4-6, and 4-7.

[0125]Each of the radio devices 0 to 9, as described above, is suitable to
wireless communication based the link state information LSIF. Therefore,
each of the radio devices 0 to 9 periodically gathers the information
about the radio devices adjacent to the radio devices 0 to 9 themselves.
Then, each of the radio devices 0 to 9 produces the link state
information LSIF consisting of the gathered information.

[0126]FIG. 10 shows an example of topology information TPIF. The radio
device 0 periodically receives the link state information LSIF from the
radio devices 1 to 9. Then, based on the received link state information
LSIF, the radio device 0 produces and maintains the topology information
TPIF indicating the arrangement of the radio devices 0 to 9.

[0127]In FIG. 10, the topology information TPIF only includes the topology
information indicating the arrangement of the radio devices 0 to 9 in
which the radio device 0 is origin. In practice, however, the topology
information TPIF includes topology information indicating the arrangement
of the radio devices 0 to 9 in which each of the radio devices 0 to 9 is
origin.

[0128]The radio device 0 produces and maintains the topology information
TPIF indicating the arrangement of all the radio devices 0 to 9 in the
wireless network system 10. In addition, in response to route requests
from the radio devices 1 to 9, the radio device 0 also detects route
information indicating routes from each of the radio devices 1 to 9 to
the destination radio device based on the topology information TPIF. The
radio device 0 then functions as the Root radio device that transmits the
detected route information to the radio device (any of the radio devices
1 to 9) that has transmitted the route request.

[0129]Then, the radio device 0 produces a route announcement packet RAE
announcing that the radio device 0 itself functions as the Root radio
device and transmits the packet to the radio devices 1 to 9. More
specifically, the routing daemon 23 of the radio device 0 produces a
route announcement packet RAE whose the Priority is set to 0 and the Flag
is set to 0, and transmits the packet to the radio devices 1 to 9.
Therefore, the radio devices 1 to 9 recognize that the radio device 0
functions as the Root radio device.

[0130]Each of the radio devices 1 to 9 periodically gathers link state
information LSIF and transmits the route announcement packet RAE
including the gathered link state information LSIF to the radio device 0.

[0131]Then, based on the link state information LSIF received from the
radio devices 1 to 9, the radio device 0 produces the above-described
topology information TPIF and maintains the topology information TPIF.

[0132]With the present invention, unlike radio device 0 functioning as the
Root radio device, the each of the radio devices 1 to 9 only gathers and
transmits to the radio device 0 the link state information LSIF: none of
the radio devices 1 to 9 maintains the link state information LSIF that
the radio devices 1 to 9 themselves have gathered, nor produces the
topology information TPIF that indicates the arrangement of all the radio
devices 0 to 9 in the wireless network system 10 by receiving link state
information LSIF from other radio devices (any of the radio devices 1 to
9).

[0133]With the present invention, the radio device 0 functioning as the
Root radio device produces the topology information TPIF based on the
link state information LSIF received from the radio devices 1 to 9 and
maintains the topology information TPIF. Then, based on the maintained
topology information TPIF, the radio device 0 transmits the route
information of the wireless network system 10 to each of the radio
devices 1 to 9.

[0134]Now, how the route for wireless communication is established between
source and destination in the wireless network system 10 will be
described. FIGS. 11A to 11D are schematic diagrams according to
Embodiment 1 illustrating how the route for wireless communication is
established between source and destination. For example, take the case
where a route is established between the radio device 3 and the radio
device 5.

[0135]With reference to FIGS. 11A to 11D, when the radio device 3
establishes the route toward the radio device 5, the routing daemon 23 of
the radio device 3 produces a route request packet

RREQ1=[ID/33/0/1/0/10/MAC Address 3/11/0/MAC Address 5/20] and transmits
the produced route request packetRREQ1=[ID/33/0/1/0/10/MAC Address
3/11/0/MAC Address 5/20]to the radio device 0 through the radio device 1.

[0136]Upon receiving the route request packet

RREQ1=[ID/33/0/1/0/10/MAC Address 3/11/0/MAC Address 5/20] from the radio
device 3, the routing daemon 23 of the radio device 1 replaces the Number
of Hops=0 to Number of Hops=1, and the Metric=0 to Metric=2 in the
[ID/10/0/1/0/10/MAC Address 3/11/0/MAC Address 5/20], to produce a route
request packet RREQ1=[ID/33/0/1/1/10/MAC Address 3/11/2/MAC Address
5/20]. Then, the routing daemon 23 of the radio device 1 transmits the
produced route request packetRREQ1=[ID/10/0/1/1/10/MAC Address 3/11/2/MAC
Address 5/20] to the radio device 0 (see FIG. 11A).

[0138]Then, the routing daemon 23 of the radio device 0 detects that the
radio device 3 is requesting a route for wireless communicate with the
radio device 5 and, based on the maintaining topology information TPIF,
extracts the optimal route (:Radio Device 3-Radio Device 4-Radio Device
7-Radio Device 5).

[0139]In this case, the route from the radio device 3 to the radio device
5 could be, for example, Radio Device 3-Radio Device 1-Radio Device
2-Radio Device 5 or Radio Device 3-Radio Device 6-Radio Device 7-Radio
Device 5, however, the routing daemon 23 of the radio device 0 extracts
the Radio Device 3-Radio Device 4-Radio Device 7-Radio Device 5 as the
optimal route considering the number of hops, statuses of the wireless
communications carried out in the past, etc.

[0142]Based on the extracted MAC Address 3-MAC Address 4-MAC Address
7-Address 5, the routing daemon 23 of the radio device 3 recognizes that
it is required by the radio device 0 to take the route Radio Device
3-Radio Device 4-Radio Device 7-Radio Device 5 for wireless communication
with the radio device 5.

[0143]Upon recognizing the route for wireless communication with the radio
device 5, the routing daemon 23 of the radio device 3 produces a route
notification packet RNTF1=[ID/44/0/10/10/4/3/MAC Address 3/10/MAC Address
3-MAC Address 4-MAC Address 7-Address 5] notifying that wireless
communication is to be carried out with the radio device 5 along the
route Radio Device 3-Radio Device 4-Radio Device 7-Radio Device 5. Then,
the routing daemon 23 of the radio device 3 sequentially transmits the
produced route notification packet RNTF1=[ID/44/0/10/10/4/3/MAC Address
3/10/MAC Address 3-MAC Address 4-MAC Address 7-Address 5] to the radio
device 4, the radio device 7 and the radio device 5.

[0144]The routing daemon 23 of the radio device 4 receives from the radio
device 3 the route notification packet RNTF1=[ID/44/0/10/10/4/3/MAC
Address 3/10/MAC Address 3-MAC Address 4-MAC Address 7-Address 5]. Based
on the MAC Address 3-MAC Address 4-MAC Address 7-Address 5 included in
the received route notification packet RNTF1=[ID/44/0/10/10/4/3/MAC
Address 3/10/MAC Address 3-MAC Address 4-MAC Address 7-Address 5], the
routing daemon 23 of the radio device 4 recognizes that packets from the
radio device 3 must be relayed to the radio device 7. Then, the routing
daemon 23 of the radio device 4 transmits the route notification packet
RNTF1=[ID/44/0/10/10/4/3/MAC Address 3/10/MAC Address 3-MAC Address 4-MAC
Address 7-Address 5] to the radio device 7.

[0145]The routing daemon 23 of the radio device 7 receives from the radio
device 4 the route notification packet RNTF1=[ID/44/0/10/10/4/3/MAC
Address 3/10/MAC Address 3-MAC Address 4-MAC Address 7-Address 5]. Based
on the MAC Address 3-MAC Address 4-MAC Address 7-Address 5 included in
the received route notification packet RNTF1=[ID/44/0/10/10/4/3/MAC
Address 3/10/MAC Address 3-MAC Address 4-MAC Address 7-Address 5], the
routing daemon 23 of the radio device 7 recognizes that packets from the
radio device 4 must be relayed to the radio device 5, which is the
destination. Then, the routing daemon 23 of the radio device 7 transmits
the route notification packet RNTF1=[ID/44/0/10/10/4/3/MAC Address
3/10/MAC Address 3-MAC Address 4-MAC Address 7-Address 5] to the radio
device 5 (see FIG. 11C).

[0146]The routing daemon 23 of the radio device 5 receives from the radio
device 7 the route notification packet RNTF1=[ID/44/0/10/10/4/3IMAC
Address 3/10/MAC Address 3-MAC Address 4-MAC Address 7-Address 5]. Based
on the MAC Address 3 included in the received route notification packet
RNTF1=[ID/44/0/10/10/4/3/MAC Address 3/10/MAC Address 3-MAC Address 4-MAC
Address 7-Address 5], routing daemon 23 of the radio device 5 recognizes
that the radio device 3 is the source. Further, based on the MAC Address
3-MAC Address 4-MAC Address 7-Address 5, the routing daemon 23 of the
radio device 5 recognizes the radio device 5 as the destination, and the
route for wireless communication with the radio device 3.

[0148]The radio device 7 receives from the radio device 5 the route reply
packet RREP1=[ID/32/0/1/MAC Address 5/40/2/0/MAC Address 3/10] and relays
the received route reply packet RREP1=[ID/32/0/1/MAC Address 5/40/2/0/MAC
Address 3/10] to the radio device 4. The radio device 4 receives from the
radio device 7 the route reply packet RREP1=[ID/32/0/1/MAC Address
5/40/2/0/MAC Address 3/10] and relays the received route reply packet
RREP1=[ID/32/0/1/MAC Address 5/40/2/0/MAC Address 3/10] to the radio
device 3 (see FIG. 11D).

[0149]The routing daemon 23 of the radio device 3 receives from the radio
device 4 the route reply packet RREP1=[ID/32/011/MAC Address 5/40/2/0/MAC
Address 3/10]. Based on the MAC Address 5(=the Destination Address)
included in the received route reply packet RREP1=[ID/32/0/1/MAC Address
5/40/2/0/MAC Address 3/10], the routing daemon 23 of the radio device 3
recognizes that the route Radio Device 3-Radio Device 4-Radio Device
7-Radio Device 5 has been established toward the radio device 5, which is
the destination.

[0150]FIG. 12 shows another example of the routing table 20. When the
route to the radio device 5 is established, the routing daemon 23 of the
radio device 3 produces a routing table 20A (see FIG. 12) in which the
destination is set to the radio device 5, the radio device adjacent to
the radio device 3 is set to the radio device 4, and the number of hops
to the radio device 5 is set to 3.

[0151]As described above, in order to establish a route for wireless
communication with the radio device 5, the radio device 3 transmits the
route request packet RREQ1 to the radio device 0 functioning as the Root
radio device and receives from the radio device 0 the route setup packet
RSET1 including the route information (=the MAC Address 3/10/MAC Address
3-MAC Address 4-MAC Address 7-Address 5) indicating the route between the
radio device 3 and the radio device 5. Then, upon receiving the route
setup packet RSET1 from the radio device 0, the radio device 3 produces
the route notification packet RNTF notifying the radio devices 4, 7 and 5
of the route established toward the radio device 5 and transmits the
packet to the radio devices 4, 7 and 5.

[0152]Then, the radio device 5, which is the destination, receives the
route notification packet RNTF1 from the radio device 3. Then, in
response to the reception of the route notification packet RNTF1, the
radio device 5 produces the route reply packet RREP1 and transmits the
packet to the radio devices 7, 4 and 3.

[0153]Therefore, a load is applied to the radio device 0 as it determines
the route between the radio device 3 and radio device 5, however, no load
is applied to the radio devices 3, 4, 7, and 5, which results in load
reduction in the overall wireless network system 10.

[0154]Here, upon receiving the route notification packet RNTF from the
radio device 4, the radio device 7 may produce the route request packet
RREQ and transmit it to the radio device 5, which is the destination. In
this case, the destination radio device 5 produces the route reply packet
RREP and transmits the packet to the radio device 7 in response to the
route request packet RREQ from the radio device 7.

[0155]As is the case with the radio device 3, the other radio devices (any
of the radio devices 1, 2, and 4 to 9) also establish the routes for
wireless communication with their respective destinations following the
above-described operation.

[0156]When the radio device 0 functioning as the Root radio device carries
out wireless communication with the other radio devices (any of the radio
devices 1 to 9), after selecting the route to the destination based on
the topology information TPIF, the radio device 0 produces the route
notification packet RNTF. Then, the radio device 0 transmits the produced
route notification packet RNTF to the destination and receives the route
reply packet RREP form the destination. In this way, the route for
wireless communication is established between the radio device 0 and the
destination.

[Another Method of Establishing Route]

[0157]The radio device 3 may establish the route for wireless
communication with the radio device 5 in accordance with the method
described below. FIGS. 13A to 13D illustrate another example of the
routing table 20. When establishing the route with this method described
below, the radio device 0 functioning as the Root radio device produces
the routing table 20 in which the destination is each of the radio
devices 1 to 9 in the wireless network system 10. Then, the radio device
0 transmits the produced routing table to each of the radio devices 1 to
9.

[0158]With reference to FIGS. 13A to 13D, the routing table 20B is
obtained when each of the radio devices 0, and 2 to 9 is the destination
of the radio device 1. The routing table 20C is obtained when each of the
radio devices 0, 1, 2, and 4 to 9 is the destination of the radio device
3. The routing table 20D is obtained when each of the radio devices 1 to
3, and 5 to 9 is the destination of the radio device 4. The routing table
20E is obtained when each of the radio devices 1 to 6, 8, and 9 is the
destination of the radio device 7.

[0159]The radio device 0 produces the routing tables 20B, 20C, 20D, and
20E and transmits the produced routing tables 20B, 20C, 20D, and 20E to
the radio devices 1, 3, 4, and 7, respectively.

[0160]It should be noted that although not illustrated in FIGS. 13A to
13D, the radio device 0 also produces routing tables indicating the
routes from the radio devices 2, 5, 6, 8, and 9 to their respective
destinations and transmits the produced routing tables to the radio
devices 2, 5, 6, 8, and 9.

[0161]When radio device 3 establishes the route for wireless communication
with the radio device 5, the routing daemon 23 of the radio device 3
determines the route to the radio device 5 by looking-up the routing
table 20C. Then, after determining the route to the radio device 5, the
routing daemon 23 of the radio device 3 produces the route notification
packet RNTF1 and transmits the packet to the radio device 4.

[0162]Upon receiving the route notification packet RNTF1 from the radio
device 3, the routing daemon 23 of the radio device 4 determines the
route to transmits the route notification packet RNTF1 to the radio
device 5 by looking-up the routing table 20D. Then, the routing daemon 23
of the radio device 4 transmits the route notification packet RNTF1 along
the determined route.

[0163]Upon receiving the route notification packet RNTF1 from the radio
device 4, the routing daemon 23 of the radio device 7 determines the
route to transmit the route notification packet RNTF1 to the radio device
5 by looking-up the routing table 20E. Then, the routing daemon 23 of the
radio device 7 transmits the route notification packet RNTF1 to the radio
device 5 along the determined route.

[0164]Upon receiving the route notification packet RNTF1, the routing
daemon 23 of the radio device 5 produces the route reply packet RREP1 and
transmits the produced route reply packet RREP1 to the radio device 3
along the route Radio Device 5-Radio Device 7-Radio Device 4-Radio Device
3. When the radio device 3 receives the route reply packet RREP1, the
route for wireless communication between the radio device 3 and the radio
device 5 is established.

[0165]As described above, when each of the radio devices 1 to 9 maintains
the routing table 20 in which the destination is each of the radio
devices, none of the radio devices 1 to 9 have to ask the radio device 0,
which functions as the Root radio device, for the route information in
order to wirelessly communicate with their destination. Therefore, the
load to the radio devices 1 to 9 is further reduced.

EMBODIMENT 2

[0166]FIG. 14 is a schematic diagram of a wireless network system
according to Embodiment 2. With reference to FIG. 14, the wireless
network system 10A is identical with the wireless network system 10 shown
in FIG. 1 except that the radio devices 1, 2, 8, and 9 of the wireless
network system 10 are replaced with the radio devices 1A, 2A, 8A, and 9A,
respectively.

[0167]FIG. 15 is a schematic block diagram illustrating the structure of
the radio devices 1A, 2A, 8A, and 9A shown in FIG. 14. Each of the radio
devices 1A, 2A, 8A, and 9A is unsuitable to wireless communication based
on the link state information LSIF. Accordingly, each of the radio
devices 1A, 2A, 8A, and 9A has the same structure as the radio devices 0
to 9 except that the routing table 20 is removed (see FIG. 2 and FIG.
15).

[0168]As a result, the wireless network system 10A comprises the radio
devices 0, and 3 and 7 suitable to wireless communication based on the
link state information LSIF, and the radio devices 1A, 2A, 8A, and 9A
unsuitable to wireless communication based on the link state information
LSIF.

[0169]Here, the radio device 0 also functions as the Root radio device in
the wireless network system 10A.

[0170]FIGS. 16A to 16D illustrate how the Root radio device gathers link
state information LSIF in Embodiment 2. With reference to FIG. 16A, the
radio devices 0, 1A, 2A, 3 to 7, 8A, and 9A constitute the wireless
network system 10A.

[0171]Under this configuration, the radio device 0 which is the Root radio
device periodically produces the route request packets RREQ and unicasts
the produced route request packets RREQ to each of the radio devices 1A,
2A, 3 to 7, 8A, and 9A (see FIG. 16B).

[0173]Accordingly, the radio devices 1A, 2A, 3 to 7, 8A, and 9A
periodically receive the route request packet RREQ from the radio device
0. Among the radio devices 1A, 2A, 3 to 7, 8A, and 9A, the radio devices
1A, 2A, 8A, and 9A are unsuitable to wireless communication based on the
link state information LSIF. Therefore, the radio devices 1A, 2A, 8A, and
9A each produce the route reply packet RREP indicating that the radio
devices 1A, 2A, 8A, and 9A themselves are unsuitable to wireless
communication based the link state information LSIF. Then, the radio
devices 1A, 2A, 8A, and 9A each unicast the packet to the radio device 0
(see FIG. 16C).

[0174]On the other hand, among the radio devices 1A, 2A, 3 to 7, 8A, and
9A, the radio devices 3 to 7 are suitable to wireless communication based
on the link state information LSIF. Therefore, the radio devices 3 to 7
produce the route reply packet RREP including periodically gathered link
state information LSIF and unicast the packet to the radio device 0 (see
FIG. 16D).

[0175]As a result, the radio device 0 receives the link state information
LSIF from the radio devices 3 to 7 suitable to wireless communication
based on the link state information LSIF. Based on the received link
state information LSIF, the radio device 0 produces and maintains the
topology information TPIF indicating the arrangement of all the radio
devices 1A, 2A, 3 to 7, 8A, and 9A in the wireless network system 10A.

[0176]Further, the radio device 0 recognizes that among the radio devices
1A, 2A, 3 to 7, 8A, and 9A constituting the wireless network system 10A,
the radio devices 1A, 2A, 8A, and 9A are unsuitable to wireless
communication based on the link state information LSIF and that the radio
devices 3 to 7 are suitable to wireless communication based on the link
state information LSIF.

[0177]It should be noted that in Embodiment 2, a radio device that is
suitable to wireless communication based on the link state information
LSIF is denoted by LS, and a radio device that is unsuitable to wireless
communication based on the link state information LSIF is denoted by NLS.
Therefore, when the radio device 0 produces the topology information TPIF
based on the link state information LSIF received from the radio devices
3 to 7, the radio devices 3 to 7 are denoted by Radio Device 3 (LS),
Radio Device 4 (LS), Radio Device 5 (LS), Radio Device 6 (LS), and Radio
Device 7 (LS) to indicate that they are the radio device LSs. Likewise,
the radio devices 1A, 2A, 8A, and 9A are denoted by Radio Device 1A
(NLS), Radio Device 2A (NLS), Radio Device 8A (NLS), and Radio Device 9A
(NLS) to indicated that they are radio device NLSs.

[0178]Therefore, when the radio device 0 extracts the route between source
and destination in response to the route request packet RREQ, it is
easily determined whether the respective radio devices constituting the
route are the radio device LS or the radio device NLS.

[0179]FIGS. 17A to 17D are schematic diagrams according to Embodiment 2
illustrating how the route for wireless communication is established
between source and destination. How the route for wireless communication
between the radio device 3 and the radio device 5 is established is
described below.

[0180]With reference to FIG. 17A, the radio device 3 produces the route
request packet RREQ1 and transmits the packet to the radio device 0
following the same operation as is explained in Embodiment 1.

[0181]Upon receiving the route request packet RREQ1 from the radio device
3, the radio device 0 produces the route setup packet RSET1 and transmits
the packet to the radio device 3 following the same operation as is
explained in Embodiment 1 (see FIG. 17B). In this case, the route setup
packet RSET1 includes route information consisting of MAC Address 3
(LS)-MAC Address 4 (LS)-MAC Address 7 (LS)-MAC Address 5 (LS). More
specifically, the route setup packet RSET1 includes information that
indicates whether the radio devices 3, 4, 7, and 5, which constitute the
route set by the radio device 0, are the radio device LS or the radio
device NLS.

[0182]The radio device 3 receives the route setup packet RSET1 from the
radio device 0. Then, in response to the reception of the route setup
packet RSET1, the radio device 3 produces the route notification packet
RNTF1 and transmits the produced route notification packet RNTF1 to the
radio device 5 along the route Radio Device 3-Radio Device 4-Radio Device
7-Radio Device 5, following the same operation as is explained in
Embodiment 1 (see FIG. 17C). In this case, the route notification packet
RNTF1 includes MAC Address 3 (LS)-MAC Address 4 (LS)-MAC Address 7
(LS)-MAC Address 5 (LS).

[0183]Upon receiving the route notification packet RNTF1 from the radio
device 3, the radio device 5 produces the route reply packet RREP1 and
transmits the packet to the radio device 3 following the same operation
as is explained in Embodiment 1 (see FIG. 17D).

[0184]The radio device 3 receives the route reply packet RREP1 from the
radio device 5, and the route for wireless communication between the
radio device 3 and radio device 5 is established.

[0185]As described above, in the wireless network system 10A, when
receiving the route request packet RREQ1 from the radio device 3 that is
suitable to wireless communication based on the link state information
LSIF, the radio device 0 functioning as the Root radio device transmits
the route setup packet RSET1 to the radio device 3 that has transmitted
the route request packet RREQ1.

[0186]In the above, it is explained that the radio device 7 relays the
route notification packet RNTF1 received from the radio device 4 to the
radio device 5. With the present invention, however, that is not always
the case and, upon receiving the route notification packet RNTF1 from the
radio device 4, the radio device 7 may produce the route request packet
RREQ1 and transmit the packet to the radio device 5. In this way, the
radio device 7 is no longer required to determine whether the radio
device 5 is the radio device LS or the radio device NLS.

[0187]More specifically, as described above, the route notification packet
RNTF1 includes the MAC Address 3 (LS)-MAC Address 4 (LS)-MAC Address 7
(LS)-MAC Address 5 (LS) and therefore, the radio device 7 is able to
determine whether the radio device 5 is the radio device LS or the radio
device NLS by looking-up the MAC Address 3 (LS)-MAC Address 4 (LS)-MAC
Address 7 (LS)-MAC Address 5 (LS) included in the route notification
packet RNTF1. When the radio device 7 produces the route request packet
RREQ1 and transmits the packet to the radio device 5, however, it is not
necessary to determine whether the radio device 5 is the radio device LS
or the radio device NLS. This is because the route notification packet
RNTF is recognized by the radio device LS only, and the route request
packet RREQ is recognized by both of the radio device LS and the radio
device NLS.

[0188]FIGS. 18A to 18D are other schematic diagrams according to
Embodiment 2 illustrating how the route for wireless communication is
established between source and destination. With reference to FIGS. 18A
to 18D, how the route for wireless communication between the radio device
1A and the radio device 8A is established is described below.

[0189]The routing daemon 23 of the radio device 1A produces a route
request packet RREQ2[ID/33/0/1/1/10/MAC Address 1A/11/2/MAC Address
8A/50] and unicasts the packet to the radio device 0 following the same
operation as the radio device 3 in accordance with Embodiment 1 (see FIG.
18A).

[0191]Then, the routing daemon 23 of the radio device 0 detects that the
radio device 1A is requesting a route for wireless communication with the
radio device 8A and, based on the maintaining topology information TPIF,
extracts the optimal route (=Radio Device 1A-Radio Device 4-Radio Device
7-Radio Device 8A).

[0192]Here, the route from the radio device 1A to the radio device 8A
could be Radio Device 1A-Radio Device 2A-Radio Device 5-Radio Device 8A
or Radio Device 1A-Radio Device 3-Radio Device 6-Radio Device 7-Radio
Device 8A, for example. The routing daemon 23 of the radio device 0
extracts, however, the route Radio Device 1A-Radio Device 4-Radio Device
7-Radio Device 8A as the optimal route considering the number of hops,
statuses of wireless communications carried out in the past, etc.

[0194]Here, the radio device 1A, which is the source, is the radio device
NLS that is unsuitable to wireless communication based on the link state
information LSIF and therefore, it is not able to recognize the route
setup packet RSET2. Accordingly, the radio device 0 transmits the route
setup packet RSET2 to the radio device 4 which is adjacent to the radio
device 1A and is the radio device LS.

[0196]Based on the extracted MAC Address 1A/MAC Address 1A (NLS)-MAC
Address 4 (LS)-MAC Address 7 (LS)-MAC Address 8A (NLS), the routing
daemon 23 of the radio device 4 recognizes that it is required by the
radio device 0 to take the route Radio Device 1A-Radio Device 4-Radio
Device 7-Radio Device 8A for wireless communication with the Radio Device
8A.

[0198]The routing daemon 23 of the radio device 7 receives from the radio
device 4 the route notification packet RNTF2=[ID/44/0/10/10/4/3/MAC
Address 4/10/MAC Address 1A/MAC Address 1A (NLS)-MAC Address 4 (LS)-MAC
Address 7 (LS)-MAC Address 8A (NLS)]. Then, based on the MAC Address
1A/MAC Address 1A (NLS)-MAC Address 4 (LS)-MAC Address 7 (LS)-MAC Address
8A (NLS) included in the received route notification packet
RNTF2=[ID/44/0/10/10/4/3/MAC Address 4/10/MAC Address 1A/MAC Address 1A
(NLS)-MAC Address 4 (LS)-MAC Address 7 (LS)-MAC Address 8A (NLS)], the
routing daemon 23 of the radio device 7 recognizes that packets received
from the radio device 4 must be relayed to the radio device 8A and that
the radio device 8A is a radio device LS.

[0199]Then, the routing daemon 23 of the radio device 7 produces a route
request packet RREQ3=[ID/44/0/1/0/60/MAC Address 7/60/0/MAC Address 8A
(NLS)/70] and unicasts the packet to the radio device 8A (see FIG. 18C).

[0200]The routing daemon 23 of the radio device 8A receives from the radio
device 7 the route request packet RREQ3=[ID/44/0/1/0/60/MAC Address
7/60/0/MAC Address 8A (NLS)/70] and, based on the MAC Address 8A included
in the received route request packet RREQ3=[ID/44/0/1/0/60/MAC Address
7/60/0/MAC Address 8A (NLS)/70],recognizes that the radio device 8A is
the destination and that a route reply packet RREP2 must be transmitted
to the radio device 7.

[0202]The radio device 7 receives from the radio device 8A the route reply
packet RREP2=[ID/32/0/1/MAC Address 8A/70/4/0/MAC Address 7/70] and
relays the received route reply packet RREP2=[ID/32/0/1/MAC Address
8A/70/4/0/MAC Address 7/70] to the radio device 4. The radio device 4
receives from the radio device 7 the route reply packet
RREP2=[ID/32/0/1/MAC Address 8A/70/410/MAC Address 7/70] and relays the
received route reply packet RREP2=[ID/32/0/1/MAC Address 8A/70/4/0/MAC
Address 7/70] to the radio device 1A.

[0203]Then, the routing daemon 23 of the radio device 1A receives from the
radio device 4 the route reply packet RREP2=[ID/32/0/1/MAC Address
8A/70/4/0/MAC Address 7/70] and, based on the MAC Address 8A (=the
Destination Address) included in the received route reply packet
RREP2=[ID/32/0/1/MAC Address 8A/70/4/0/MAC Address 7/70], recognizes that
the route for wireless communication with the radio device 8A, which is
the destination, has been established.

[0204]As described above, if the source radio device is unsuitable to
wireless communication based on the link state information LSIF, the
radio device 0 functioning as the Root radio device transmits the route
setup packet RSET to a radio device (=the radio device 4) that is
adjacent to the source and is suitable to wireless communication based on
the link state information LSIF. In response to the reception of the
route setup packet RSET, the radio device 4 produces and transmits the
route notification packet RNTF.

[0205]The radio device 8A, which is the destination, is unsuitable to
wireless communication based on the link state information LSIF.
Therefore, in response to the reception of the route notification packet
RNTF, the radio device 7 adjacent, on the route, to the radio device 8A,
which is the destination, produces a route request packet RREQ and
transmits the packet to the radio device 8A that is the destination. The
radio device 8A then produces and transmits the route reply packet RREP
in response to the reception of the route request packet RREQ.

[0206]In this way, even when the source and/or the destination is a radio
device that is unsuitable to wireless communication based on the link
state information LSIF, the route for wireless communication could be
established between source and destination along the route set by the
radio device 0.

[0207]It should be noted that, in Embodiment 2, the radio device 0 may
also produce a routing table in which the sources are each of the radio
devices 3 to 7 suitable to wireless communication based on the link state
information LSIF and the destinations are each of the radio devices 1A,
2A, 3 to 7, 8A, and 9A, and transmit the produced routing table to the
radio devices 3 to 7. Based on the routing table received from the radio
device 0, the radio devices 3 to 7 may establish the route for wireless
communication with their respective destinations.

[0208]According to Embodiment 2, even when the network comprises the radio
devices 3 to 7 suitable to wireless communication based on the link state
information and the radio devices 1A, 2A, 8A, and 9A unsuitable to
wireless communication based on the link state information, the radio
device 0 functioning as the Root radio device produces and maintains the
topology information TPIF that indicates the arrangement of all the radio
devices 0, 1A, 2A, 3 to 7, 8A, and 9A in the wireless network system 10A.
Then, in response to route requests from the radio devices 1A, 2A, 3 to
7, 8A, and 9A, the radio device 0 extracts the optimal routes by
looking-up the topology information TPIF and transmits to the radio
devices 3 to 7 the route information indicating the extracted optimal
routes. The radio devices 3 to 7 establish the routes for wireless
communication between source and destination.

[0209]Therefore, the load to the radio devices 1A, 2A, 3 to 7, 8A, and 9A
is reduced, which results in load reduction in the overall wireless
network system 10A.

[0210]Here, preferably, the wireless network system 10A is configured so
that the radio devices 3 to 7, which are suitable to wireless
communication based on the link state information LSIF are adjacent to
the radio devices 1A, 2A, 8A, and 9A, which are unsuitable to wireless
communication based on the link state information LSIF. With such a
configuration, when the route is established for wireless communication
between source and destination, the plurality of radio devices that are
unsuitable to wireless communication based on the link state information
LSIF will never be adjacent to each other on the route. Therefore, even
when the source is a radio device unsuitable to wireless communication
based on the link state information LSIF, the radio device 0 is only
required to transmits the route setup packet RSET to a radio device that
is adjacent to the source and is suitable to wireless communication based
on the link state information LSIF, and the route is established between
source and destination with accuracy.

[0211]It should be noted that, in the above, it is explained that the
radio devices 0 to 9 have the structure shown in FIG. 2. With the present
invention, however, that is not always the case, and the radio devices 0
to 9 may have the structure as shown in FIG. 19. FIG. 19 is another
schematic block diagram illustrating the structure of the radio devices 0
to 9 shown in FIG. 1.

[0212]With reference to FIG. 19, each of the radio devices 0 to 9
comprises a communication unit 30, an address analyzer 31, a routing
controller 32, and a routing table 33.

[0214]The address analyzer 31 analyzes the addresses of the packet PKT,
the route request packet RREQ, the route reply packet RREP, the route
setup packet RSET, the route notification packet RNTF, and the route
announcement packet RAE, which are received from the communication unit
30, and transmits the analysis result to the routing controller 32.

[0215]Based on the analysis result received from the address analyzer 31,
the routing controller 32 produces and maintains the topology information
TPIF. Then, based on the topology information TPIF, the routing
controller 32 produces the route setup packet RSET including route
information that indicates the route for wireless communication between
source and destination, and transmits the packet to the communication
unit 30.

[0216]Upon receiving from the address analyzer 31 the MAC address of a
radio devices constituting the route indicated by the route information
included in the route setup packet RSET, the routing controller 32 also
produces the routing table 33 based on the received MAC address.

[0217]Further, based on the analysis result received from the address
analyzer 31, the routing controller 32 produces the above-described route
request packet RREQ, route reply packet RREP, and route announcement
packet RAE and transmits the packets to the communication unit 30.

[0218]The routing table 33 stores the route information indicating the
routes to the respective destinations and has the same structure as the
routing table 20 described above.

[0219]In the above, it is explained that the radio devices 1A, 2A, 8A, and
9A have the structure shown in FIG. 15. With the present invention,
however, that is not always the case, and the structure of the radio
devices 1A, 2A, 8A, and 9A may be as shown in FIG. 20. FIG. 20 is another
schematic block diagram illustrating the structure of the radio devices
1A, 2A, 8A, and 9A shown in FIG. 14.

[0220]With reference to FIG. 20, each of the radio devices 1A, 2A, 8A, and
9A is identical with the radio devices 0 to 9 shown in FIG. 19 except
that the routing table 33 of the radio devices 0 to 9 is removed.

[0221]In the above, it is explained that the topology information TPIF is
produced based on the MAC address in Layer 2 to establish the route for
wireless communication between source and destination. With the present
invention, however, that is not always the case, and the topology
information TPIF may be produced based on the IP address to establish the
route for wireless communication between source and destination.

[0222]Further, in the above, it is explained that the radio devices 1A and
3, which are the sources, produce the route request packet RREQ and
transmit the packet to the radio device 0. With the present invention,
however, that is not always the case, and the radio devices 1A and 3,
which are the sources, may produces a packet PKT including a message
requesting the notification of the route to the radio devices 5 and 8A,
which are the destinations, and transmit the packet to the radio device
0.

[0223]Further, in the above, it is explained that either the radio device
3 that is the source or the radio device 4 that is adjacent to the radio
device 1A, which is the source, transmits the route notification packet
RNTF notifying of the route for wireless communication between source and
destination. With the present invention, however, that is not always the
case, and either the radio device 3 that is the source or the radio
device 4 that is adjacent to the radio device 1A, which is the source,
may transmit a packet PKT including the route for wireless communication
between source and destination as a message.

[0224]Further, in the above, it is explained that the radio devices 5 and
8A that are the destinations produce the route reply packet RREP and
transmit the packet to the radio devices 3 and 1A that are the sources.
With the present invention, however, that is not always the case, and the
radio devices 5 and 8A that are the destinations may produce a packet PKT
including a message acknowledging the route setup and transmit the packet
to the radio devices 3 and 1A that are the sources.

[0225]The embodiments as have been described here are mere examples and
should not be interpreted as restrictive. The scope of the present
invention is determined by each of the claims, not by the written
description of the embodiments, and embraces modifications within the
meaning of, and equivalent to, the languages in the claims.

INDUSTRIAL APPLICABILITY

[0226]The present invention is applied to the wireless network system that
enables load reduction.

Patent applications by Bing Zhang, Tokyo JP

Patent applications by Seiji Igi, Tokyo JP

Patent applications by Youiti Kado, Tokyo JP

Patent applications by NATIONAL INSTITUTE OF INFORMATION AND COMMUNICATIONS TECHNOLOGY

Patent applications by OKI ELECTRIC INDUSTRY CO., LTD.

Patent applications in class Contiguous regions interconnected by a local area network

Patent applications in all subclasses Contiguous regions interconnected by a local area network